Re: [PATCH 06/10] mtd: intel-dg: wake card on operations

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Oct 22, 2024 at 01:41:15PM +0300, Alexander Usyskin wrote:
> Enable runtime PM in mtd driver to notify graphics driver that
> whole card should be kept awake while nvm operations are
> performed through this driver.
> 
> CC: Lucas De Marchi <lucas.demarchi@intel.com>
> Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
> ---
>  drivers/mtd/devices/mtd-intel-dg.c | 73 +++++++++++++++++++++++++-----
>  1 file changed, 61 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mtd/devices/mtd-intel-dg.c b/drivers/mtd/devices/mtd-intel-dg.c
> index 4951438e8faf..3d53f35478e8 100644
> --- a/drivers/mtd/devices/mtd-intel-dg.c
> +++ b/drivers/mtd/devices/mtd-intel-dg.c
> @@ -15,11 +15,14 @@
>  #include <linux/module.h>
>  #include <linux/mtd/mtd.h>
>  #include <linux/mtd/partitions.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/string.h>
>  #include <linux/slab.h>
>  #include <linux/sizes.h>
>  #include <linux/types.h>
>  
> +#define INTEL_DG_NVM_RPM_TIMEOUT 500
> +
>  struct intel_dg_nvm {
>  	struct kref refcnt;
>  	struct mtd_info mtd;
> @@ -462,6 +465,7 @@ static int intel_dg_mtd_erase(struct mtd_info *mtd, struct erase_info *info)
>  	loff_t from;
>  	size_t len;
>  	size_t total_len;
> +	int ret = 0;
>  
>  	if (WARN_ON(!nvm))
>  		return -EINVAL;
> @@ -476,20 +480,28 @@ static int intel_dg_mtd_erase(struct mtd_info *mtd, struct erase_info *info)
>  	total_len = info->len;
>  	addr = info->addr;
>  
> +	ret = pm_runtime_resume_and_get(mtd->dev.parent);
> +	if (ret < 0) {
> +		dev_err(&mtd->dev, "rpm: get failed %d\n", ret);
> +		return ret;
> +	}
> +
>  	guard(mutex)(&nvm->lock);
>  
>  	while (total_len > 0) {
>  		if (!IS_ALIGNED(addr, SZ_4K) || !IS_ALIGNED(total_len, SZ_4K)) {
>  			dev_err(&mtd->dev, "unaligned erase %llx %zx\n", addr, total_len);
>  			info->fail_addr = addr;
> -			return -ERANGE;
> +			ret = -ERANGE;
> +			goto out;
>  		}
>  
>  		idx = idg_nvm_get_region(nvm, addr);
>  		if (idx >= nvm->nregions) {
>  			dev_err(&mtd->dev, "out of range");
>  			info->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
> -			return -ERANGE;
> +			ret = -ERANGE;
> +			goto out;
>  		}
>  
>  		from = addr - nvm->regions[idx].offset;
> @@ -505,14 +517,18 @@ static int intel_dg_mtd_erase(struct mtd_info *mtd, struct erase_info *info)
>  		if (bytes < 0) {
>  			dev_dbg(&mtd->dev, "erase failed with %zd\n", bytes);
>  			info->fail_addr += nvm->regions[idx].offset;
> -			return bytes;
> +			ret = bytes;
> +			goto out;
>  		}
>  
>  		addr += len;
>  		total_len -= len;
>  	}
>  
> -	return 0;
> +out:
> +	pm_runtime_mark_last_busy(mtd->dev.parent);
> +	pm_runtime_put_autosuspend(mtd->dev.parent);
> +	return ret;
>  }
>  
>  static int intel_dg_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
> @@ -541,17 +557,25 @@ static int intel_dg_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
>  	if (len > nvm->regions[idx].size - from)
>  		len = nvm->regions[idx].size - from;
>  
> +	ret = pm_runtime_resume_and_get(mtd->dev.parent);
> +	if (ret < 0) {
> +		dev_err(&mtd->dev, "rpm: get failed %zd\n", ret);
> +		return ret;
> +	}
> +
>  	guard(mutex)(&nvm->lock);
>  
>  	ret = idg_read(nvm, region, from, len, buf);
>  	if (ret < 0) {
>  		dev_dbg(&mtd->dev, "read failed with %zd\n", ret);
> -		return ret;
> +	} else {
> +		*retlen = ret;
> +		ret = 0;
>  	}
>  
> -	*retlen = ret;
> -
> -	return 0;
> +	pm_runtime_mark_last_busy(mtd->dev.parent);
> +	pm_runtime_put_autosuspend(mtd->dev.parent);
> +	return ret;
>  }
>  
>  static int intel_dg_mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
> @@ -580,17 +604,25 @@ static int intel_dg_mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
>  	if (len > nvm->regions[idx].size - to)
>  		len = nvm->regions[idx].size - to;
>  
> +	ret = pm_runtime_resume_and_get(mtd->dev.parent);
> +	if (ret < 0) {
> +		dev_err(&mtd->dev, "rpm: get failed %zd\n", ret);
> +		return ret;
> +	}
> +
>  	guard(mutex)(&nvm->lock);
>  
>  	ret = idg_write(nvm, region, to, len, buf);
>  	if (ret < 0) {
>  		dev_dbg(&mtd->dev, "write failed with %zd\n", ret);
> -		return ret;
> +	} else {
> +		*retlen = ret;
> +		ret = 0;
>  	}
>  
> -	*retlen = ret;
> -
> -	return 0;
> +	pm_runtime_mark_last_busy(mtd->dev.parent);
> +	pm_runtime_put_autosuspend(mtd->dev.parent);
> +	return ret;
>  }
>  
>  static void intel_dg_nvm_release(struct kref *kref)
> @@ -722,6 +754,17 @@ static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
>  		n++;
>  	}
>  
> +	pm_runtime_enable(device);
> +
> +	pm_runtime_set_autosuspend_delay(device, INTEL_DG_NVM_RPM_TIMEOUT);
> +	pm_runtime_use_autosuspend(device);

something looks strange here...
on the functions above you get and put references for the parent device directly.
But here you enable the rpm for this device.

If I remember correctly from some old experiments, the rpm is smart enough
and wake up the parent before waking up the child. So I'm wondering if we should
only do the child without the parent.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Anshuman Gupta <anshuman.gupta@intel.com>

> +
> +	ret = pm_runtime_resume_and_get(device);
> +	if (ret < 0) {
> +		dev_err(device, "rpm: get failed %d\n", ret);
> +		goto err_norpm;
> +	}
> +
>  	nvm->base = devm_ioremap_resource(device, &invm->bar);
>  	if (IS_ERR(nvm->base)) {
>  		dev_err(device, "mmio not mapped\n");
> @@ -744,9 +787,13 @@ static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
>  
>  	dev_set_drvdata(&aux_dev->dev, nvm);
>  
> +	pm_runtime_put(device);
>  	return 0;
>  
>  err:
> +	pm_runtime_put(device);
> +err_norpm:
> +	pm_runtime_disable(device);
>  	kref_put(&nvm->refcnt, intel_dg_nvm_release);
>  	return ret;
>  }
> @@ -758,6 +805,8 @@ static void intel_dg_mtd_remove(struct auxiliary_device *aux_dev)
>  	if (!nvm)
>  		return;
>  
> +	pm_runtime_disable(&aux_dev->dev);
> +
>  	mtd_device_unregister(&nvm->mtd);
>  
>  	dev_set_drvdata(&aux_dev->dev, NULL);
> -- 
> 2.43.0
>